Surgical procedures invariably involve a certain amount of trauma to tissues and organs at and around the surgical site. Minimizing surgical trauma is an important goal because it helps to minimize the risk of complications and helps reduce the postsurgical healing period. Trauma is of particular concern in surgical procedures involving the eye because of the delicate nature of that organ and its constituent parts.
Several surgical procedures in the eye involve entering the eye through a small incision through the cornea or front of the eye and proceeding past the plane of the iris and through the pupil. Cataract removal and implantation of a replacement lens, such as an intraocular lens, is one example of such a procedure.
To avoid injury to the iris, a critical but weak and delicate organ controlling the amount of light entering the eye, in procedures passing through or near the iris, it is desirable to dilate the pupil to keep the iris out of harm's way and to give the surgeon a wider opening through which to work and view the posterior segments of the eye. During an eye surgery procedure, the eye surgeon may dilate the iris chemically using a mydriatic. However, this dilation method is limited in time and offers no protection to the iris against the invasive procedures.
Mechanical dilators or retractors have also been developed. For example, U.S. Pat. No. 4,387,706 discloses an iris retractor comprising a substantially circular, resilient ring which is compressed or deformed while inserting through an incision in the cornea, where it is then worked into an abutting relationship with the iris, where compression forces are released to allow the retractor to return to its normal (expanded) shape, forcing the iris open. U.S. Pat. No. 4,782,820 discloses an adjustable iris retractor which preferably has a pair of separable, slideably interengaged ends which allows sliding movement to increase or decrease the diameter of the retractor. U.S. Pat. Nos. 3,490,455; 4,037,589; 4,257,406; and 4,991,567 disclose various conventional clamps, tacks and mechanical devices typical of other conventional retractors used in a variety of surgical procedures. Such conventional mechanical dilators and retractors are expensive to manufacture, cumbersome to use, traumatic to the iris, and often require large incisions for insertion and use.
In view of the deficiencies of the prier art, it would be desirable to have a mechanical iris dilator, which is easy to manufacture and is easy and safe to use.